1. Field of the Invention
This invention relates to a radiation image recording and read-out system, in which dynamic image recording and read-out operations are performed with X-rays, or the like. This invention also relates to a computer program for the radiation image recording and read-out system.
2. Description of the Related Art
An arthrosteitis is an ordinary symptom that adversely affects a joint of a human. The arthrosteitis constitutes a principal cause of a pain at the time of motions and a motion failure. Particularly, the arthrosteitis of a knee often occurs with persons of middle age and advanced age.
However, in spite of the frequent occurrence of the arthrosteitis, little information is available with respect to factors for the advance of the arthrosteitis. In particular, it has heretofore been considered that there is no technique for the degeneration disease due to wear and loss. However, recently, it is often regarded that there is possibility of the arthrosteitis being treated with pharmaceutical or surgical treatment utilizing cartilage transplantation, bone resection, tibial corticectomy, and the like. However, whether a treatment technique for the arthrosteitis is or is not capable of being selected appropriately depends upon a technique for evaluating the condition of a joint of a patient and a degeneration process. Therefore, it is necessary to develop a technique for investigating factors, which affect the advance of the arthrosteitis and a technique for quantitative determination of the advance of the arthrosteitis. Particularly, it has been found that kinetic loads have relations with the advance of the arthrosteitis. Accordingly, information concerning relations with a load region in a motion cycle is markedly important for the evaluation of the factors, which affect the advance of the arthrosteitis.
Also, a joint is constituted of cartilages and accompanying bones, which are located on opposite sides of the joint. Therefore, for the evaluation of the condition of the joint, there has been proposed a technique for acquiring information concerning the load region from a joint motion pattern and a joint cartilage degeneration pattern by use of magnetic resonance images (MRI), CT images, and the like. Specifically, there has been proposed a technique, wherein relationship between the joint motion pattern and the joint cartilage degeneration pattern is acquired from a comparison of the joint motion pattern and the joint cartilage degeneration pattern with each other, external markers are located on the skin at the accompanying bone for detection of the joint motion pattern, and the joint motion pattern is acquired with the passage of time from movements of the external markers. (The technique described above is proposed in, for example, International Patent Publication No. WO/00/035346.)
The technique utilizing the magnetic resonance images (MRI) is a markedly accurate technique for visualizing the joint cartilage suffering from the arthrosteitis at, particularly, a knee region. In particular, for kinetic analyses of knee joints, a kinetic MRI technique, or the like, has heretofore been utilized for examinations.
However, in the cases of the CT examinations and the MRI examinations, a long time is required for reservations, or the like, before the persons to be examined become capable of undergoing the examinations, and the examination cost is not capable of being kept low. If the kinetic analyses are capable of being performed as screening examinations, the examinations will be capable of being conducted markedly efficiently.
Therefore, currently, as kinetic examination modalities, flat panel detectors (FPD's) adapted to dynamic images are considered to be promising. In cases where the FPD's adapted to dynamic images are utilized, there is a high possibility that the kinetic analyses will be performed easily as in the cases of the ordinary X-ray examinations. Accordingly, the FPD's adapted to dynamic images are capable of being utilized for the screening examinations.
In cases where the X-ray image recording operations aiming at the kinetic analyses described above are to be performed, for example, successive image recording operations are performed at a frame rate ranging from approximately 3 fps (frames per second) to approximately 30 fps. Also, kinetic analyses are made in accordance with the acquired images, and diagnoses are made in accordance with the results of the kinetic analyses. However, with the image recording techniques aiming at the kinetic analyses described above, the following problems are encountered:                An image of the joint at a desired position is not capable of being recorded due to the manner of movement of the joint of the person to be examined.        Since the successive image recording operations are performed at a predetermined frame rate, it often occurs that an image of the object at a required position is not capable of being acquired, and it becomes necessary for the image recording operations to be performed again.        
Further, if the successive image recording operations are performed by use of ordinary radiation doses, with which the images of the object are capable of being recorded clearly, the total radiation dose delivered to the person to be examined will become high. Therefore, it is desired that the image recording operation with the ordinary radiation dose is capable of being performed only at the time at which the position of the object coincides with a required position.